1. Field of the Invention
The present invention relates to an imaging apparatus having a subject detection function and a zoom function. Further, the present invention relates to a method of controlling the imaging apparatus to perform the subject detection function and the zoom function.
2. Description of the Related Art
There is a conventional imaging apparatus (such as a digital camera) that has an optical zoom function and an electronic zoom function. The optical zoom function is an optical magnification varying function that can be realized by driving a zoom lens to change the focal length of the camera. The electronic zoom function is an electronic magnification varying function that enlarges a part of an imaged area digitally by cropping an image with no adjustment of the camera's optics. Recent improvement in zoom lens performance enables a photographer to perform a shooting operation using the same lens in an enlarged range from a super wide angle end to a super telephoto end. Further, the highly increased number of pixels of newer image sensors enables a photographer to perform a shooting operation in satisfactory resolution even when magnification is high.
However, even with advanced optical and semiconductor improvements, movement of either the subject or the camera represents a challenge during imaging. As discussed in Japanese Patent Application Laid-Open No. 2012-60595, it is conventionally known to immediately recapture a subject when the subject goes out of the frame. The above-mentioned function is referred to as framing assist (FA) zoom function (hereinafter, referred to as an FA zoom function). The apparatus discussed in Japanese Patent Application Laid-Open No. 2012-60595 can cause the zoom position of a camera to zoom out toward the wide angle direction in response to an instruction to start the FA zoom function, and can cause the zoom position to zoom in toward the original zoom position (i.e., to the zoom position set at the start timing of the FA zoom function) in response to an instruction to terminate the FA zoom function.
On the other hand, it is also known that when a camera detects a subject in the screen, the camera can automatically change the zoom position according to information about the detected subject. Such a function is conventionally known as automatic zoom function. Further, as discussed in Japanese Patent No. 1881884, it is conventionally known to cause the zoom position to zoom out toward the wide angle direction when a subject has reached a limit position of a specific area of the screen. Further, as discussed in the Japanese Patent No. 2052653, it is conventionally known to cause the zoom position to zoom in toward the telephoto direction when a subject is located at a central region of the screen.
The methods discussed in Japanese Patent Application Laid-Open No. 2012-60595 and Japanese Patent No. 1881884 are characterized by manually changing the specific area of the screen (i.e., a zoom start area) to be set to detect a subject and determine to start a zoom operation. Further, in a case where information about a detected human face is used to realize the automatic zoom function, if the zoom start area is set at an upper part of the screen, a photographer performs a shooting operation with a composition in which the bust of a human or the whole body is included, the face area may enter the zoom start area and the camera may erroneously start a zoom-out operation. On the other hand, when a photographer performs a shooting operation while holding the camera in a hand, the subject may enter the zoom start area due to camera shake or similar situation. In this case, the photographer can perform a framing operation in such a way as to correct the degree of frame out. However, if the camera immediately performs a zoom-out operation, the photographer may feel it troublesome.